1. Field of the Invention
The invention in general relates to sonar transducers, and particularly to a transducer of the longitudinal resonator type which can be used at various depths in the ocean.
2. Description of the Prior Art
A common type of sonar transducer is the longitudinal resonator or Tonpilz type of transducer which includes a head mass for projection and/or receipt of acoustic energy, a tail mass operative as an inertial element and active transducer means interposed between, and coupled to, the head and tail masses. The active transducer means is generally composed of a stack of rings of a ceramic piezoelectric material having interposed electrodes to which electrical connections are made.
One type of sonar system utilizes a plurality of such transducer units arranged in a vertical, cylindrical array utilized for omni-directional transmission and/or reception and comprised of a series of vertical staves with each stave containing a predetermined number of the transducer units.
Each individual transducer unit of the array is contained within its own housing with the front surface of the head mass facing radially outward from the cylindrical array. If the array is utilized for a variable depth search operation, a situation may arise wherein the transduces of the array exceed a design depth limit or are subject to an explosive shock. In such situations, not only is performance degraded, but the transducer itself is subject to irreparable damage.
The present invention provides for an improved Tonpilz type transducer which can be used in an array and which is protected from damage in an over-depth or explosive shock situation.